1. Field of the Invention
The present invention relates to petrophysical reservoir characterization, and, in particular, to on-site permeability measurements obtained of core samples collected from formation rock adjacent well bores in subsurface reservoirs to determine formation areas of interest.
2. Description of the Related Art
In the petroleum extraction and production industry, ascertaining the subterranean characteristics of reservoirs is of vital economic importance. Characteristics such as formation rock permeability and porosity help to indicate subsurface areas of increased fluid movement. In order to locate these areas, the permeability and porosity of the reservoir rock must be determined. Permeability refers to the ability of the reservoir rock to transmit fluids through many large interconnected pore spaces. Porosity is a measure of the capacity of the reservoir rock which is able to store oil and gas, or in other words, the volume of the pore space in a porous medium.
In current reservoir analysis methods, so far as known, porosity and permeability measurements have been determined by removing core samples from a well drilled into a reservoir rock formation of interest. So far as known, once these samples had been removed, they were transported to a testing facility which was at a laboratory and not at the site of the well. Once the samples were transported to the laboratory, the technician or scientist could begin conducting various tests to determine the permeability of the reservoir samples.
There were many disadvantages to this type of reservoir analysis. First, preserving the fresh and original state of the core sample is highly important in ascertaining various data, such as water quality, biocide functioning, and microbial activity. However, during transportation to the experiment lab, maintaining the original state was very difficult. Also, the test fluids used in the lab tests might differ to an appreciable extent from the actual fluids at the reservoir or to be used at the reservoir. Further, in current analysis methods, the time it took to transport the samples to the laboratory resulted in lost time and higher production costs. Drilling companies spend vast amounts of money each day performing drilling operations; therefore, any way to reduce this time would be advantageous. Additionally, the present testing systems, so far as is known, are too large and cumbersome to be efficiently transported on-site to conduct testing.